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Diagnostic Pathology 2011, 6:76
doi:10.1186/1746-1596-6-76

Published: 11 August 2011

Abstract

Background

The accuracy of melanoma diagnosis continues to challenge the pathology community,
even today with sophisticated histopathologic techniques. Melanocytic lesions exhibit
significant morphological heterogeneity. While the majority of biopsies can be classified
as benign (nevus) or malignant (melanoma) using well-established histopathologic criteria,
there exists a cohort for which the prediction of clinical behaviour and invasive
or metastatic potential is difficult if not impossible to ascertain on the basis of
morphological features alone. Multiple studies have shown that there is significant
disagreement between pathologists and even expert dermatopathologists in the diagnosis
of this subgroup of difficult melanocytic lesions.

Methods

A four probe FISH assay was utilized to analyse a cohort of 500 samples including
157 nevus, 176 dysplastic nevus and 167 melanoma specimens.

Results

Review of the lesions determined the assay identified genetic abnormalities in a total
of 83.8% of melanomas, and 1.9% of nevus without atypia, while genetic abnormalities
were identified in 6.3%, 6.7%, and 10.3% of nevus identified with mild, moderate and
severe atypia, respectively.

Conclusions

Based on this study, inheritable genetic damage/instability identified by FISH testing
is a hallmark of a progressive malignant process, and a valuable diagnostic tool for
the identification of high risk lesions.